From hollow to dense spheres: Control of dipolar interactions by tailoring the architecture in colloidal aggregates of superparamagnetic iron oxide nanocrystals

Abstract

The control of dipolar interactions by fabrication of colloid aggregates of superparamagnetic iron oxide nanocrystals was studied. The direct synthesis by aerosol pyrolysis of spherical aggregates containing nanomagnets with similar crystal size was described. A comprehensive analysis of the different magnitude of the dipolar interactions was carried out with the help of a mean field model. The model allows to estimate dipolar interactions in a temperature region, within which the behavior of interacting nanomagnets was described by the interacting superparamagnetic regime (ISP).